Calculating Elastic Energy: Where Did I Go Wrong?

[Clara Chung]

Homework Statement

Homework Equations

The Attempt at a Solution

I tried to use the equation introduced in the class, E=σε/2
ε=αΔT =2*10^-5*200 = 4*10^-3
and by σ=Yε, I get σ=110*10⁹*4*10^-3 = 4.4*10⁹
so E=(4*10^-3) * (4.4*10⁹ ) /2 = 880000J
Why am I wrong?
The correct answer is 35.2 J

 

[Chestermiller]

Better check your units. Also, you determined the stored energy per unit volume.

 

[Clara Chung]

Better check your units. Also, you determined the stored energy per unit volume.

Thanks!